Make particles wiggle (in a sine wave)
I would tackle this problem by using a curve guide force field where Kink is set to Wave. Frequency and Amplitude will help you to shape your movement.

I prepared a blend for you that illustrates the behaviour clearly and upload it here 
http://www.pasteall.org/blend/29048

This screenshot should help all of you that don't like to download foreign blend files ;)


Consider that the wave kind is behaving like a sawtooth wave... so maybe you should form your curve guide like the sine wave you'd like to create.

Another way is to use a harmonic field... for a demo of this effect, look here: http://www.pasteall.org/blend/29061 The movements here are less uniform. If you need even more turbulence use the turbulence field on top..